Oh what a great question… and yet quite a controversial one! A lot of essential oils are photosensitizing, and I feel should therefore not be applied during the day (to the face). But you are quite right, there are quite a few brands that load their products with essential oils and that puts at risk any patients who are prone to pigmentation and skin sensitivity. I don’t see any issue with using essential oils at night, provided you cleanse your skin in the morning and wear a very good facial SPF every single day. To be perfectly honest with you, it also very much depends on the technology behind the product. If you are buying a product off a supermarket or pharmacy shelf that is loaded with essestial oils for use on your face, I would be very cautious of that product. If you are using a cosmeceutical that has to be purchased from a medical aesthetic clinic, then there is a good reason why a specific oil is in that product and it has almost certainly been formulated accordingly to protect the patient’s skin. For example, the Lamelle Clarity Range has a bit of tea tree in the product, but it has been very safely formulated and the amount that is in the product is not going to give you any issues at all. I hope I’ve answered you adequately?